Willenburg, Castle ruin in Schiltach, Germany.

Willenburg is a ruined hill castle about 2 km outside Schiltach, above the old Schiltacher Steige pass road toward Aichhalden. Excavations from 1959 to 1970 uncovered foundations and wall sections measuring 36 by 20 metres. Visitors see wall remains, ramparts and a 30.3-metre-deep castle well.

The fortress was built around 1100 by the Dukes of Teck or Zähringen to control key trading routes through the region. It functioned as a toll station for merchants traveling toward Rottweil.

The name Willenburg is not explained in the sources; the castle is also called Schlössle. It served travellers on the old pass road to Rottweil, where tolls were raised. After Schiltach took over this role around 1250, the site decayed and was later called a Burgstall, a lost castle. The Museum am Markt in Schiltach displays finds from the excavations.

The ruins are best reached on foot, with a trail leading uphill through the forest to the site. Wear sturdy shoes and allow time for the climb, as the path is steep and exploring the remnants takes patience.

The castle well is 30.3 metres deep, a figure recorded during the excavations of 1959 to 1970 that also uncovered foundations measuring 36 by 20 metres. Pottery found in the rubble helped date the site. Finds from the dig are displayed at the Museum am Markt in Schiltach.